Poor Longwall Productivity and Claystone Roof Rock: A Need for Geotechnical Analysis.
Paper in Proc 1989 :21-26
Longwall failures can occur when shield supports are used in inappropriate strata conditions. This U.S. Bureau of Mines paper is a case study of one such failure. Shield rotation resulted in poor longwall production rates in a mine with fractured claystone roof rock. The fractured claystone, with abundant fossilized root casts, was further weakened by its tendency to swell upon contact with mine air at the longwall face. The immediate claystone roof rock crushed between an overlying massive, cantilevering main roof rock and the stiff shields. The loss of confinement in this low tensile and shear strength roof rock was aggravated by the use of four-leg shield supports. These factors have combined to cause the claystone roof rock to disintegrate into small blocks. These blocks then became dislodged and fell onto the conveyor. This action created an irregular roof surface for the shields to pressurize against, causing them to rotate out of position. Straightening rotated shields caused extensive production delays. Solutions to the problem consist of utilizing shield designs that best support this type of rock or avoidance of these areas by longwall mining techniques. Advanced planning to utilize these solutions could be accomplished with progressive geotechnical techniques prior to the selection of equipment and the start of mining. The matching of appropriate mining systems with specific strata conditions can minimize the unanticipated instability problems and greatly diminish the potential for future longwall failures.
Paper in Proc., 1989 Multinational Conf. on Mine Planning & Design; Univ. Kentucky, 1989, PP. 21-26
We take your privacy seriously. You can review and change the way we collect information below.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
Cookies used to make website functionality more relevant to you. These cookies perform functions like remembering presentation options or choices and, in some cases, delivery of web content that based on self-identified area of interests.
Cookies used to track the effectiveness of CDC public health campaigns through clickthrough data.
Cookies used to enable you to share pages and content that you find interesting on CDC.gov through third party social networking and other websites. These cookies may also be used for advertising purposes by these third parties.